Hedyotis diffusa (also called Bai Hua She She Cao) has a long history of use in Traditional Chinese Medicine (TCM), particularly for "clearing heat and toxin" and as an adjunct in the management of various swellings and lumps, including breast lumps. In TCM theory, breast lumps, especially those considered benign, are thought to arise from "stagnation of phlegm and blood stasis," and Hedyotis diffusa is commonly included in herbal formulations intended to address these imbalances. The herb is believed to have anti-inflammatory, detoxifying, and anti-tumor properties according to TCM practices.

While there are increasing numbers of laboratory and some animal studies suggesting that extracts of Hedyotis diffusa may exhibit anti-cancer effects, including inhibition of cancer cell proliferation and induction of apoptosis, these studies are mainly preclinical. For breast lumps specifically, there is currently insufficient high-quality clinical trial evidence to conclusively demonstrate its efficacy and safety. Most of the clinical data available are from case series, traditional records, or studies lacking rigorous controls.

In summary, the use of Hedyotis diffusa for breast lumps is primarily supported by traditional use and TCM theory, with some emerging preclinical scientific interest, but robust human clinical evidence is currently limited.